Atypical ("pseudosarcomatous") cutaneous histiocytoma

We report a patient with a cytologically atypical hemosiderotic histiocytoma that histologically suggested a sarcoma. The lesion is differentiated from atypical fibroxanthoma and fibroxanthosarcoma. We wish to emphasize the benign nature of this variant of histiocytoma whose extreme cellular atypicality may simulate a sarcoma.